Fast nanoimprinting methods using deformable mold

ABSTRACT

Methods for nanoimprint lithography using a deformable mold. Generally, the method includes a deformable mold fixed firmly onto a hollow mold holder around its full periphery is attached to top inner surface of the chamber and positioned underneath the transparent section. The central area of the mold is freely accessible from underneath through the opening of the mold holder. At beginning of the imprinting, the substrate with a layer of resist is positioned underneath the mold at a predetermined gap between them and a substrate is moved up to contact with the mold either under vacuum or under atmosphere. After consolidating the resist, the substrate is separated from the mold by either direct pull-down enabled by stage movement or deforming the mold enabled by differential pressure between the mold mini-chamber and the bulk volume of the chamber, or mixing of both.

CROSS-REFERENCE FOR RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No. 13/011,844filed on Jan. 21, 2011, which issued as U.S. Pat. No. 8,747,092 on Jun.10, 2014; which claimed the of U.S. Provisional Application Ser. No.61/297,398 filed on Jan. 22, 2010, each of which is incorporated hereinby reference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH

This invention was made with Government support under contractW31P4Q-06-C-0104 awarded by the Defense Advanced Research ProjectsAgency (DARPA). The Government has certain rights in the invention.

FIELD

This invention relates to methods and apparatus for imprint lithography.It is particularly useful for providing fast replication of patterns ofa mold having microscale or nanoscale features by imprint lithography.

BACKGROUND

Nanoimprint lithography, also often called imprint lithography, iscapable of replicating patterns on a pre-made mold as small as severalnanometers. The pre-made mold has extruded areas and recessed areas onits replication surface, which constitute patterns of various shapes andsizes. The mold was typically made by a patterning step using electronbeam lithography (EBL) or mixing of EBL and optical lithography, and, afollow-up etching step using reactive ion etching (RIE) to create thepatterns. Nanoimprint lithography starts from applying a volume ofpolymer onto a substrate by either spinning or dispensing. The polymeris either flowable in ambient temperature, or, from rigid to deformableor flowable by thermally heating, Then, the pre-made mold is positionedto contact with the substrate. After that, the mold is pressed againstthe substrate. If the polymer is in liquid in ambient temperature,pressing the mold against the substrate will force the surface extrusionareas on the mold replication surface to go into the layer of thepolymer. If the polymer is rigid in ambient temperature, a thermallyheating step is conducted prior to the contact, after the contact butbefore the pressing, or during the pressing to make the polymerdeformable or flowable. Thus, pressing the mold against the mold is ableto force the surface extrusion areas on the mold replication surface togo into the layer of the polymer. When the extruded areas completely gointo the layer of the polymer, the polymer transits from deformable orflowable into rigid by UV radiation, thermally heating or thermallycooling depending on types of the polymer. At last, the mold is releasedfrom the substrate while the layer of the polymer attaches to thesubstrate. To prevent the polymer from sticking to the mold, a very thinrelease coating may be deposited on the replication surface of the mold.Typical release coating included surface release surfactant andper-fluoro polymer deposited by CVD. After the substrate is separatedfrom the mold, the extrusion areas on the mold surface is correspondingto the recessed areas in the polymer layer. Therefore, a reverse-tonereplication of the patterns on the mold is formed onto the polymer filmon the substrate. The polymer may be a thermo-plastic polymer or curabletemperature. A thermo-plastic polymer transits from rigid to deformableor flowable when being heated above its glass transition temperature,and, vice versus when is cooled below its glass transition temperature.A curable polymer is deformable or flowable originally, and transit torigid when being heating to curing temperature for thermo-set type andbeing cured under UV exposure for UV-curable type. When alignment isneeded, the mold is aligned with the substrate through a set of matchingalign markers prior to the contact. Previously, electron beamlithography is very slow to write nanoscale patterns. It is unlikely touse it for mass production of nanoscale devices. Nanoimprint lithographyis able to replicate whole area of patterned surface of the pre-mademold onto the substrate by one cycle of the process. It can dramaticallyincrease the efficiency of patterning nanoscale features. Because themold is repeatedly used for many cycles of imprinting, the high cost ofusing electron beam lithography to make the mold is averaged into thesemany imprints. Nanoimprint lithography delivers a practical method toproduce nanoscale devices at low cost.

Since its invention in 1995 by Stephen Y. Chou (referring to U.S. Pat.No. 5,772,905), nanoimprint lithography has successfully demonstratedits capability of replicating a feature as small as 5 nm. Meanwhile,many research works were spent on developing resists for imprinting,mold making techniques, mold release coating for clean separation, andapparatus to do imprinting. In overall, nanoimprint lithography hasevolved into being a widely used technology for research laboratories,but not reached a stage ready to meet much higher requirements ofindustrial use. One of the critical improvements needed by industrialuse is imprint apparatus with high throughput and overlay accuracy.

Fast nanoimprint apparatus is highly demanded by semiconductor industryto use this technology to manufacture nano-scale device products. Priorto the invention, the apparatus of nanoimprint lithography conductedaligning and contacting the mold with the substrate and pressing themold against the substrate on two different sites within frame of theapparatus. Separating the mold from the substrate was often conducted oneither one site of them or a third site. This basic design approachdemanded to transfer the contacted mold/substrate set among these sitesto finish a full cycle of operation. Thus, throughput of the apparatus,which is defined as time consumption to finish a cycle of imprinting, isseverely degraded by time cost of transferring among these differentsites. Furthermore, the internal transferring increases mechanicalcomplexity of the apparatus and potentially introduces mechanicalfailure during operation. An apparatus capable of completing a fullcycle of imprinting process on one site within its frame limit willpotentially achieve much higher throughput and reliability.

BRIEF SUMMARY OF THE DISCLOSURE

The disclosed methods are for nanoimprint lithography using a deformablemold. Generally, the apparatus has a chamber with a transparent sectionon its top wall, which is capable of vacuuming and pressurizing. Thedeformable mold fixed firmly onto a hollow mold holder around its fullperiphery is attached to top inner surface of the chamber and positionedunderneath the transparent section. The central area of the mold isfreely accessible from underneath through the opening of the moldholder. An enclosed volume referring to mold mini-chamber is formedbetween the mold/holder and top wall of the chamber. Inside chamber, astage assembly is installed. A chuck to vacuumly hold a substrate ismounted on top of the stage assembly. At beginning of the imprinting,the substrate with a layer of resist is positioned underneath the moldat a predetermined gap between them. Then, the substrate is moved up tocontact with the mold either under vacuum or under atmosphere. Thesubstrate and mold may be pressed further by introducing higher pressureinside the chamber. After consolidating the resist, the substrate isseparated from the mold by either direct pull-down enabled by stagemovement or deforming the mold enabled by differential pressure betweenthe mold mini-chamber and the bulk volume of the chamber, or mixing ofboth.

In one aspect, a method for imprinting a substrate having a moldablesurface with a mold having a molding surface, wherein the periphery ofsaid mold is attached on a mold fixture located inside a chamber andconnected to said chamber, said mold fixture comprises a first interfaceseal to seal the attached periphery and a second interface seal to sealthe interface between said fixture and said chamber. The methodincluding disposing said substrate inside said chamber and adjacent saidmold such that said moldable surface is adjacent said molding surfaceand adjusting the gap between said moldable surface and said moldingsurface. The method also including removing gas from the space betweensaid moldable surface and said molding surface. The method furtherincluding forming contact between said moldable surface and said moldingsurface and imprinting said molding surface against said moldablesurface by pressing said mold and said substrate together withpressurized gas. The method also including deforming assembly of saidmold and said substrate that are pressed together by said step ofimprinting, said deforming is effected by implementing differential gaspressure between two sides of said assembly to have a least portion ofthe peripheral of said substrate released from said mold and separatingsaid moldable surface away said molding surface.

Further aspects of the present disclosure will be in part apparent andin part pointed out below. It should be understood that various aspectsof the disclosure may be implemented individually or in combination withone another. It should also be understood that the detailed descriptionand drawings, while indicating certain exemplary embodiments, areintended for purposes of illustration only and should not be construedas limiting the scope of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The features, nature and advantages of the invention will be moreclearly understood by consideration of the illustrative embodiments nowto be described in detail in connection with the accompanying drawing.In the drawing:

FIG. 1 is schematic drawing of the apparatus illustrating the invention;

FIG. 2a-2d illustrates operation process of the apparatus illustratingthe invention;

FIG. 3 is a flow chart to show a process to realize contacting step ofthe operation process.

FIG. 4 is a flow chart to show an alternative process to realizecontacting step of the operation process.

FIG. 5 is a flow chart to show a process to realize separation step ofthe operation process.

FIG. 6 is a flow chart to show alternative processes to realizeseparation step of the operation process.

It is to be understood that these drawings are for purposes ofillustrating the concept of the invention and are not to scale.

DETAILED DESCRIPTION OF THE DISCLOSURE

The descriptions assume that UV curable imprint is conducted if it isnot clearly identified and UV curable imprint is used as example.However, the invention does not limit for UV curable imprint and alsoapply for thermo-plastic imprint. An ordinary skilled in the art who isfamiliar with nanoimprint technology can easily revise the embodimentdescribed in the invention to implement the concept of the invention forall type of imprinting.

In accordance with the concept of the invention, referring to FIG. 1,the apparatus has a chamber 10 that can achieve vacuum or pressureinside. The top wall of the chamber has a light passing through section11. Section 11 could be a transparent window made of quartz or glass.The section is able to hold vacuum seal and built-up pressure inside thechamber during operation. Section 11 allows a UV light passing throughto provide UV curing exposure for UV curable imprint and a visible lightpassing through to view inside of the chamber 10. For such purpose, a UVradiation source 12 is mounted outside chamber 10 and right abovesection 11. An alternative mounting for UV source 12 is to mount thesource 12 elsewhere and use a plurality of minors to deflect UV light topass through section 11. In case of doing thermal imprint, the UVradiation source 12 is replaced by heating lamp. Secondarily, section 11allows viewing inside of the chamber 10 for alignment using microscopes,process monitoring using cameras or laser sensors, or both. A mold 30for imprinting is firmly held around its full periphery against a moldholder 20 by using a mechanical clamp means. The mold holder 20 ishollow to permit a central patterned region 31 of mold 30 to be freelyaccessible from underneath side or both sides. The mold 30 may beinstalled on or uninstalled from the mold holder 20 for eitherreplacement or cleaning. During operation, the mold holder 20 with themold 30 installed is loaded into the chamber 10 and firmly attached toinner surface of top wall of the chamber 10. The mold holder 20 ispositioned to have patterned region 31 exposable through section 11 andaccessible from underneath. An enclosed volume named mold mini-chamber16 is formed by body of mold holder 20, mold 30 and top inner surface ofthe chamber wall. Being contrast with mold mini-chamber 16, the restbulky inner volume of the chamber 10 is referred to chamber volume 15.The chamber 10 is connected to a pressure pump 33 with pneumatic lines37, 38 that independently control pumping or pressurizing of moldmini-chamber 16 and chamber volume 15, respectively. Therefore, both ofthem can be pumping to vacuum and pressurized and a differentialpressure between them can be established when desired. Inside thechamber 10, a stage assembly 21 is mounted onto the bottom wall of thechamber 10. The stage assembly 21 is coupled to a stage assemblycontroller 40 via a control line 42 and at least contains a Z motioncontrol in order to accomplish desired process of the apparatus. Thestage assembly 21 may further contain X-Y motion controls in order to doalignment. A chuck 23 with vacuum grooves on its top surface is mountedon a leveler 22 which in turn is mounted on the stage assembly 21.Leveler 22 is to provide a limited adjustment of surface parallelism ofthe substrate 32. Leveler 22 may be removed when mechanical assemblingaccuracy of the apparatus is sufficient to accomplish desired process. Asubstrate 32 for imprinting is held on chuck 23 by vacuumly pumpingthrough the vacuum grooves. The stage assembly 21 is either mechanicallyinstalled or capable of moving the substrate 32 within its X-Y travelranges to superimpose the center of the substrate 32 with the center ofpatterned region 31 in X-Y plane. The substrate 32 may have a moldablematerial 35 applied on its side surface facing the mold 30 beforeimprint begins. The moldable material 35 could be a continuous filmlayer of imprinting resist spun on or a plurality of droplets ofimprinting resist dispensed on. When the moldable material 35 is in formof a plurality of droplets before imprinting, the spacial relation ofthe distribution of the droplets could be a uniform matrix of equalspacing among adjacent droplets along one direction or multi directions,or an arbitrary matrix optimized for merging each to achieve desiredimprinted patterns. In addition to these general demands for imprinting,the spacial relation is preferred to deliver a uniform and continuouscontacting interface between the mold 30 and the substrate 32 during theimprint process of the apparatus.

Imprint process of the apparatus is illustrated in serial drawings ofFIGS. 2a, 2b, 2c, and 2d . Referring to FIG. 2a , mold holder 20 withmold 30 installed is loaded into chamber 10 and firmly attached to topplate of the chamber wall. Substrate 32 with moldable material 35 on itstop surface is held against chuck 23 by pumping through the vacuumgrooves and positioned beneath the opening of mold holder 20. Atbeginning of the imprint process of the apparatus, substrate 32 ispositioned to a starting position which normally has a 1-2 millimetergap between the substrate and the mold and the center of the substratesuperimposing with the center of the mold.

Referring to FIG. 2b , next step of the imprint process is to pumpchamber volume 15 and mold mini-chamber 16 to remove air. This pumpingstep facilitates to reduce trapped air defects of imprinted patterns.Aligning the substrate 32 with the mold 30 can be finished before thepumping or in the pumping. Normally, aligning the substrate 32 and themold 30 is accomplished by positioning an align marker on the substrate32 overlapping with a matching align marker on the mold 30 undermicroscopes. To prevent possible shift of the substrate 32 on chuck 23during the pumping, the substrate 32 is moved up and contacts with themold 30 under a controlled push by the stage assembly 21 before chambervolume 15 reaches a better vacuum than the vacuum grooves. Referring toFIG. 3, an alternative way to form the contact is realized by deformingthe mold 30. Referring to step 310, the substrate 32 is positioned tohave a predetermined gap between the mold 30 and the substrate 32. Tocontrol the gap at a predetermined distance, by way of example, ameasurement subsystem 44 such as shown in FIG. 1, can include, by way ofexample, a laser/sensor combination assembly 46 located within thechamber 10 is coupled to the measurement subsystem 44 via communicationline 48 to measure the distance between the molding surface of the mold30 and the moldable surface of the substrate 32 and provides measurementdata to the pressure pump 33 and/or the stage assembly controller 40.Then, referring to step 311, the mold 30 is deformed to press againstthe substrate 32 by implementing a differential vacuum or pressurebetween mold mini-chamber 16 and chamber volume 15. The center of themold 30, where has the most significant deformation, firstly contactswith the substrate 32. As the differential vacuum or pressure increases,the contact expands from the center to periphery. At a specificdifferential vacuum or pressure, full area of the substrate 32 contactswith the deformed mold 30. The differential vacuum and pressurenecessary to establish the full area contact is determined by majorfactors such as overall dimensions, peripheral clamping, body thicknessand material of the mold 30, gap prior to deforming mold 30, and,overall dimensions of the substrate 32. During establishing the fullarea contact, moldable material 35 under press of the contactredistributes to form an intermediate layer of continuous film. Next,referring to step 312, pumping back side of the substrate 32 through thevacuum grooves is removed to make the substrate 32 releasable from thechuck 23. At last, referring to step 313, the mold is restored to itsoriginal shape by removing the differential vacuum or pressure whileretaining the contact with the substrate 32. The intermediate moldablematerial 35 provides adhesion necessary to retain the contact betweenthe mold 30 and the substrate 32.

Referring to FIG. 4, another alternative way to accomplish the contactstep of FIG. 2b is to deform the mold 30 at a predetermined extent andmove the substrate 32 up against the deformation. At first, referring tostep 410, the mold 30 is deformed toward the substrate 32 to apredetermined extent by implementing a differential pressure or vacuumbetween mold mini-chamber 16 and chamber volume 15. The optimalcondition for the predetermined extent of deformation is affected bysubstrate thickness variations and variations of surface parallelismbetween mold 30 and substrate 32. The predetermined extent ofdeformation prefers to have the center of the mold deformed downward by0.05-0.5 millimeters. Then, referring to step 411, substrate 32 is movedup to contact with deformed mold 30 at its center where maximumdeformation occurs. After that, referring to block 412, moving substrate32 up is coordinated with reducing the differential pressure or vacuumso that contacted area between the mold 30 and the substrate 32 expandsaccordingly until reaching full area of the substrate 32. The step canbe realized by repeating small changes of moving the substrate 32 andreducing the differential pressure or vacuum. It is desired that themold 30 is restored to its original shape when the full area contact isreached. The process of making the contact does not depend on adhesionprovided by intermediate moldable material 35 and is able to squeeze anyresidual air out of interim region between the mold 30 and the substrate32. Thus, it may be conducted at atmosphere without causing serioustrapped air defects for imprinted patterns.

When the contact step of FIG. 2b is accomplished, the moldable material35 has been pressed lightly and redistributed to fill space between themold 30 and the substrate 32. For case of using very low viscositymoldable material 35, the press caused by the contact may be sufficientto imprint patterns of the mold 30 into the moldable material 35. Inorder to guarantee quality of patterns imprinted, it may need to applyhigher pressure press on the mold 30 and the substrate 32 than thecontact.

Referring to FIG. 2c , higher pressure press is applied on the mold andthe substrate by filling mold mini-chamber 16 and chamber volume 15 withhigh pressure gas. Air Cushion Press (ACP) is realized during this stepfor imprinting. Details of Air Cushion Press are described by Stephen Y.Chou in U.S. Pat. No. 6,482,742 under a title of “Fluid Pressure ImprintLithography”, which is herein incorporated by reference. The ACPrealized herein does not use a film or O-ring to seal edge in order forACP to work properly. Instead, it depends on the prior contact and theintermediate moldable material to seal the contacting periphery of themold and the substrate. This improvement of eliminating film or O-ringis very significant for the apparatus to achieve higher throughput andreliability. Chuck 23 may be moved away from contacting the back side ofthe substrate during this step so as not to degrade pressing uniformityof ACP. After reaching desired pressure for ACP, the moldable materialredistributes to completely fill every space between the mold and thesubstrate, then, is consolidated to solid by a UV exposure throughsection 11. Finally, the high pressure gas for ACP is vented toatmosphere. So far, pattern formation of imprinting is completed. Thesubstrate is ready for releasing from the mold.

Referring to FIG. 2d , the substrate 32 is separated from the mold 30.The separation can be realized by combining mold 30 deformation andstage movement. FIG. 5 illustrates a way to separate the substrate 32from the mold 30. Referring to step 501 of FIG. 5, the separation startsfrom positioning chuck 23 underneath substrate 32 at a predeterminedgap. Then, referring to step 502, a differential pressure between moldmini-chamber 16 and chamber volume 15 is introduced to deform the mold30. As deformation is enlarged by increasing the differential pressure,substrate 32 loses contact from the mold 30 starting from periphery andexpanding toward center. Meanwhile, substrate 32 is lowered down untilit is supported by chuck 23. The differential pressure reaches apredetermined value so that back side of substrate 30 completelycontacts with chuck 23. By now, a significant peripheral region of thesubstrate 32 is released from the mold 30 and central region of thesubstrate 32 is not yet. After that, referring to step 503, thesubstrate 32 is held against chuck 23 by pumping back side of thesubstrate 32 through the vacuum grooves on the chuck surface. Finally,referring to step 504, the established differential pressure is removedto restore the mold 30 backward its original shape. Because thesubstrate 32 is vacuumly held against the chuck 23, the remainingcentral area of the substrate 32 is separated from the mold 30. Thesubstrate 32 stays on chuck 23 after the separation and the mold 30 isreturned to its starting status.

Alternative ways to separate the substrate from the mold 30 areillustrated in FIG. 6. These ways share a common concept that usevacuuming to hold back side of the substrate 32 and pull it to separateusing the stage assembly 21. This concept works for this scenariobecause the mold 30 is deformable. The mold 30 may be intentionallydeformed to facilitate the separation. Referring to step 601 of FIG. 6,the separation starts from vacuumly holding back side of substrate 32against top surface of chuck 23 by pumping through the vacuum groves onthe chuck 23. If chuck 23 is away from the substrate 32, the chuck 23 ispositioned to contact back side of the substrate 32 by the stageassembly 21 prior to the vacuumly holding. Referring to step 604, oneway to separate is to pull substrate 32 downward by moving the stageassembly 21 down. Because the substrate 32 is held against the vacuumgrooves on the chuck 23 and the mold 30 is deformable, at beginning ofthe pull, the mold 30 is deformed so that periphery of the substrate 32is separated first. As the downward pulling is progressing, theseparated region of the substrate 32 propagates from the firstlyseparated periphery inner ward the center. At end of the downwardpulling, the substrate 32 is completely separated from the mold 30. Toimprove this separation process, referring to step 602 prior to step604, a predetermined differential pressure is implemented between moldmini-chamber 16 and chamber volume 15 to deform the mold 30 againstchuck 23. Present of the differential pressure makes the mold 30 moreeasily deformable when the substrate 32 is pulled downward. Thus, theseparation is improved to be more easily and reliably. The differentialpressure is predetermined so that the mold 30 is not under risk ofrupture when the substrate 32 is separated and the chuck 23 is movedaway. Referring to step 603, it can also implement a reversedifferential pressure between mold mini-chamber 16 and chamber volume 15to deform the mold 30 away chuck 23. In such way, the mold 30 is moreeasily deformed away the substrate 32 to improve the separation when thesubstrate 32 is pulled downward. This reverse differential pressure ispredetermined not to risk the mold 30 for any possible rupture when thesubstrate 32 is separated. For this case, a supporting surface could bespecially designed on inner top wall of the chamber 10 to limit maximumreverse deformation of the mold 30. After the substrate 32 is separatedfrom the mold 30, any differential pressure implemented previously isremoved to restore the mold 30 to its original shape.

The mold 30 used for the apparatus is deformable under a reasonabledifferential pressure between it two sides. The mold could be made ofquartz, glass, polymer or metal. Obviously, to be used to do UV imprint,the mold has to have a reasonable UV transmission, which excludes usingmetal mold and prefers to use quartz, glass or UV transmissible polymersuch as a specially made PMMA. If metal mold is used to do thermalimprint, the mold prefers to use Ni as mold material which has beenwidely used for compact disk (CD) manufacturing. To meet the criteria ofdeformable, overall dimensions, opening region on mold holder, and bodythickness should be considered as a whole for the mold to be deformableunder the process conditions of the apparatus. One example of the molduses 8″ diameter quartz or glass wafer with a substrate thickness 0.2-1mm and has a 6″ or 7″ diameter circular opening region free to deformwhen it is installed on the mold holder. Another example of the molduses 12″ diameter quartz or glass wafer with a substrate thickness 0.2-2mm and has a 10″ circular opening region free to deform when it isinstalled on the mold holder. One more example of the mold uses 8″diameter Ni substrate with a thickness 0.1-1 mm and has a 6 or 7″diameter circular opening region free to deform when it is installed onthe mold holder.

The improvements possessed by the invention are emphasized again herein.The apparatus embodiments described in the invention accomplish a fullcycle of imprinting inside the chamber through a process essentiallyinvolving deforming the mold and positioning the substrate by the stageassembly. The speed to finish each step of the process is primarilydecided by stage response and how fast to deform the mold. Usingstate-of-art stage technology, stage response can be very fast andcapable of responding to requests of each step in seconds. By reducingeffective volume of mold mini-chamber 16, deforming the mold is alsovery fast through adjusting gas pressure inside the mold mini-chamberrelative to the chamber volume. Thus, the process of the apparatus toaccomplish a full cycle of imprinting could be very fast. Furthermore,the chamber uses vacuum to eliminate possibility of trapping air betweenthe mold and the substrate. The intrinsic Air Cushion Press (ACP) of theprocess provides very uniform imprinting force which is crucial toachieve the pattern fidelity required by manufacturing. Eliminatingneeds of using a film or o-ring to seal edge for proper ACP is also asignificant improvement to have fast imprinting cycle and long-timereliable operation.

It is to be understood that the above described embodiments areillustrative of only a few of the many embodiments that can representapplications of the invention. Numerous and varied other arrangementscan be made by those skilled in the art without departing from thespirit and scope of the invention.

What is claimed is:
 1. A method for imprinting a substrate having amoldable surface with a mold having a molding surface, wherein theperiphery of said mold is attached on a mold fixture located inside achamber and connected to said chamber, said mold fixture comprises afirst interface seal to seal the interface between the mold fixture andthe attached periphery of the mold and a second interface seal to sealthe interface between said mold fixture and said chamber, comprising thesteps of: disposing said substrate onto a substrate chuck inside saidchamber and adjacent said mold such that said moldable surface isadjacent said molding surface; adjusting the gap between said moldablesurface and said molding surface; removing gas from the space betweensaid moldable surface and said molding surface; forming contact betweensaid moldable surface and said molding surface; imprinting said moldingsurface against said moldable surface by pressing said mold and saidsubstrate together with pressurized gas to form a mold substrateassembly; following the imprinting, deforming the assembly of said moldand said substrate that are pressed together by said step of imprintinguntil releasing at least a portion of the peripheral region of saidsubstrate release from said mold, said deforming and said release areboth effected by implementing differential gas pressure between the moldside of said assembly and the substrate side of said assembly; andfollowing the deforming and the releasing of at least a portion of theperipheral of the substrate from the mold of the mold substrateassembly, separating said moldable surface away from said moldingsurface.
 2. The method of claim 1 further comprising a step of hardeningsaid moldable surface after said step of imprinting and before said stepof deforming.
 3. The method of claim 1 wherein said step of separatingcomprises the steps of: retaining non-contacted side of said substratewith the substrate chuck by vacuuming the substrate chuck; and reducingthe deformation generated in said step of deforming assembly of saidmold and said substrate while maintaining said retaining until saidsubstrate is fully separated from said mold.
 4. The method of claim 1wherein said step of separating comprises the steps of: retainingnon-contacted side of said substrate with the substrate chuck; andpulling said substrate away from said mold to separate by moving saidchuck transversely away said mold.
 5. The method of claim 1 wherein saidstep of separating comprises the steps of: retaining non-contacted sideof said substrate with the substrate chuck; increasing said differentialgas pressure of said step of deforming assembly; and pulling saidsubstrate away from said mold to separate by moving said substrate chucktransversely away from said mold.
 6. The method of claim 1 wherein saidstep of forming contact is effected by reducing the gap between saidmoldable surface and said molding surface until said moldable surfacecontacts with said molding surface.
 7. The method of claim 6 whereinsaid step of separating comprises the steps of: retaining non-contactedside of said substrate with the substrate chuck by vacuuming thesubstrate chuck; and reducing the deformation generated in said step ofdeforming assembly of said mold and said substrate while maintainingsaid retaining until said substrate is fully separated from said mold.8. The method of claim 1 wherein said step of forming contact comprisesthe steps of: adjusting the gap between said moldable surface and saidmolding surface to a predetermined value; deforming said mold towardsaid substrate to form contact between said moldable surface and saidmolding surface; and releasing the deformation generated in said step ofdeforming while retaining the contact formed in said step of deformingsaid mold.
 9. The method of claim 8 wherein said step of separatingcomprises the steps of: retaining non-contacted side of said substratewith a vacuum chuck; and reducing the deformation generated in said stepof deforming assembly of said mold and said substrate while maintainingsaid retaining until said substrate is fully separated from said mold.10. The method of claim 1 wherein said step of forming contact comprisesthe steps of: deforming said mold toward said substrate by implementingdifferential gas pressure between two sides of said mold; moving saidsubstrate toward said mold to form initial contact at center of saidmold; reducing the deformation effected by said deforming said mold; andcoordinately, moving said substrate toward said mold to follow thereduction of said deformation.
 11. The method of claim 10 wherein saidstep of separating comprises the steps of: retaining non-contacted sideof said substrate with the substrate chuck by vacuuming the substratechuck; and reducing the deformation generated in said step of deformingassembly of said mold and said substrate while maintaining saidretaining until said substrate is fully separated from said mold. 12.The method of claim 1 wherein the process of adjusting the gap betweenthe moldable surface and said molding surface includes adjusting aspatial relationship to deliver a uniform and continuous contact of theinterface along the molding surface and the moldable surface during theimprinting process.
 13. The method of claim 1 wherein the process ofremoving gas from the space between said moldable surface and saidmolding surface reduces trapped air from imprinted patterns on themolding surface of the mold.
 14. The method of claim 1 wherein the stepof forming contact between the moldable surface of the substrate and themolding surface of the mold is via a controlled push of the substratetowards the mold and that the forming of the contact is made before thestep of removing gas from the space between said moldable surface andsaid molding surface reaches a vacuum that is greater than a vacuumretaining the substrate in a fixed position within the chamber, at whichpoint the substrate is released from the substrate chuck forming themold substrate assembly.
 15. The method of claim 1 wherein following theimprinting and prior to the deforming, further comprising releasing thesubstrate from the substrate chuck so that the mold substrate assemblyis solely held within the chamber by the mold fixture, wherein the stepof deforming using differential pressure includes creating adifferential pressure between a backside of the mold forming amini-chamber and the chamber in which the substrate is disposed.
 16. Themethod of claim 15 wherein following the releasing of the substrate andthe deforming, wherein the separating includes bringing the substratechuck into contact with the substrate and applying a vacuum pressurefrom the substrate chuck onto the substrate to aid in the separating ofthe moldable surface of the substrate from the molding surface of themold.
 17. The method of claim 15, following the releasing of thesubstrate and prior to the deforming, applying a high pressure gaswithin the chamber and within a mini-chamber on the non-contact side ofthe mold for applying a high pressure to both sides of the assembly. 18.The method of claim 1 wherein the deforming the assembly of said moldand said substrate that are pressed together by said step of imprintingincludes implementing the differential gas pressure that is a reversedifferential pressure between two sides of said assembly such that themold is deformed away from the substrate.
 19. A method for imprinting asubstrate having a moldable surface with a mold having a moldingsurface, wherein the periphery of said mold is attached on a moldfixture located inside a chamber and connected to said chamber, saidmold fixture comprises a first interface seal to seal the interfacebetween the mold fixture and the attached periphery of the mold andthereby sealing a mold mini-chamber formed on a side of the moldopposite to the molding surface and a second interface seal to seal theinterface between said mold fixture and said chamber for sealing thechamber, comprising the steps of: disposing said substrate on asubstrate chuck inside said chamber and adjacent said mold such thatsaid moldable surface is adjacent said molding surface; adjusting thegap between said moldable surface and said molding surface; removing gasfrom the space between said moldable surface and said molding surface;forming contact between said moldable surface and said molding surface;following the forming of contact, releasing the substrate from thesubstrate chuck so that the substrate is solely held by a moldablematerial between said substrate and said mold; following the releasingof the mold substrate assembly, imprinting said molding surface againstsaid moldable surface by pressing said mold and said substrate togetherwith pressurized gas to form a mold substrate assembly; following theimprinting, deforming the assembly of said mold and said substrate untilreleasing at least a portion of the peripheral region of said substratefrom said mold, said deforming and said releasing of at least a portionof the peripheral of said substrate from said mold are both effected byimplementing differential gas pressure between the mold mini-chamber andthe chamber and therefore between the two sides of said assembly; andfollowing the deforming and the releasing of at least a portion of theperipheral of the substrate from the mold of the mold substrateassembly, separating said moldable surface away from said moldingsurface.